| Provincial Situation: |
Infestations occur in all agricultural ecoregions of the province, with the exception of mixed and moist mixed grasslands (Table 1). The relative abundance index and the ranking of common chickweed in various agricultural ecoregions is as follows:
Table 1. The relative abundance and Ranking of common chickweed in Alberta.
| Agricultural Ecoregion | Rank | Frequency1 (%) | Uniformity2 | Density3 (m-2) | Relative Abundance | | | | | (%) | | | | Mixed Grassland | - | - | - | - | - | | Moist Mixed Grassland | - | - | - | - | - | | Fescue Grassland | 13 | 5.3 | 31.3 | 13.3 | 6.5 | | Aspen Parkland | 1 | 31.1 | 51.5 | 38.8 | 40.6 | | Boreal Transition | 1 | 55.2 | 52 | 25.2 | 50.8 | | Peace Lowland | 6 | 25.6 | 42.2 | 20 | 18 | | Alberta (All regions) | 3 | 21.2 | 49.1 | 31 | 29.4 |
1 Frequency = Percent of fields in which Common chickweed occurred
2Density = Average number of Common chickweed in occurrence fields.
3Uniformity = percent of quadrates in which Common chickweed occurred Source: Thomas et al (2002). Alberta Weed Surveys. Cereal, Oilseed and Pulse Crops 2001s. |
| Description: |
Common chickweed is a mat-forming plant up to 12 inches tall. Stems are prostrate, rooting at the nodes, usually with a single line of hairs along each internode. Leaves are opposite, egg-shaped to elliptic; up to 1½ inch long, hairy. The lower leaves are stalked, but the upper leaves are stalkless. The small, white, star-shaped flowers have 5 petals that are so deeply cleft they appear as 10. The capsules are egg-shaped; straw colored and up to ¼ inches long. The capsule contains many tiny reddish brown seeds |
| Growth and Development (Life Cycle): |
Emergence: Shoots from horizontal roots appear on the soil surface around mid-April and continue to emerge throughout the summer. Seed germinate from late May through fall.
Seed Production: Single plant of chickweed is capable of producing from 600-15 000 seeds.
Seed germination: Seed of chickweed are viable as soon as they are shed. Buried seeds require light before germination can occur. Most seed germinate within three yrs. after they are shed. The optimum temperature for germination is between 12 to 20 degree C. High temperatures are inhibitory and germination does not occur when temperature exceeds 30 degrees C. Optimum depth for germination is 0.5 to 1.0 cm, with very few seeds germinating at depths greater than 2.5 cm.
Dormancy: Shed seeds of chickweed have 90 to 100% viability
Longevity in the soil: Seeds are capable of remaining viable in the soil for more than 60 years.
Dispersal: Seeds are dispersed in a number of ways: by footwear, thought the digestive tracks of birds (sparrows, quail, and gulls), cattle, horses, and pigs Seeds are also known to be dispersed by ants and earthworms. The seed is also spread as a contaminant in pasture seed mixtures or seeds of the other crops. |
| How it Spreads (Mode of Spread): |
The common chickweed is often spread via the sale of contaminated crop seeds. |
| Reproduction (Dispersal): |
Seed: Common chickweed reproduces mainly by seeds. Seed output of chickweed can be from 600 to 15 000 seeds/plant.
Vegetative: Vegetative reproduction by fragmentation of stems can also occur |
| Economic Importance (Beneficial Aspects): |
Detrimental: In Canada, common chickweed is a weed of grain fields, and pasture. It can be a major contaminant among some crops such as barley and potato crops. Common chickweed competes with crop by shading and smothering young seedling with a mat like growth. It is especially troublesome in barley crops. Barley and chickweed grows at the same level, however, chickweed roots grows faster. Common chickweed seeds are contaminants in the seeds of wheat, barley, rye, oats, oats timothy, rape mustard sugar beet and kale. Chickweed may contain toxic concentration of poisonous glycosides and nitrates, reported to have caused digestive disorders when eaten in large quantities by lambs.
Beneficial: It can prevent soil erosion. It is source of food for animals. The plant being eaten by hogs, chickens, and the birds. Man sometimes uses the plant for salad |
| Origin: |
Common chickweed is native to Europe. Seed of this species has been reported in the pre-glacial deposits in Britain. How and when this species was introduced into North America is not known. It was reported from New England in 1n 1672. It was common in Montreal area in 1821 and in Nova Scotia in 1829. It was listed as the farm weed in Canada in 1909. |
| Flowering: |
Flowering timing: Flower appears 4-5 weeks after emergence. Flower opens only for one day. |
| Yield Losses: |
Chickweed is not a strong competitor in established crops and grows only in bare patches, but seedling crop can be smothered when chickweed forms a mat and cover them. Chickweed is a problem because it remains green and wrap around the moving parts of the harvest equipments. If the weather is cool and wet, chickweed will grow in swaths and delay drying time and make pick-up difficult. |
| How to Control: |
Use an integrated weed management approach that focuses on the prevention of seed production and the establishment of a competitive crop stand.
Mowing: Close mowing will help to reduce seed set of chickweed, however, plants close to soil surface may not be cut.
Tillage: Tillage is not compatible with direct seeding systems, because it promotes soil erosion. However, in conventional tillage systems, tillage can be used to suppress this weed.
Early shallow tillage encourages germination of weed seeds. When seedling emerges the land should be tilled again and then seeded. Post seeding tillage is not effective for controlling chickweed. Since chickweed plants are dragged and not buried and easily re-roots from stem nodes. Fall tillage is important to control chickweed that would otherwise set seed or over-winter.
Crop rotation: Strong stand of perennial crops are beneficial in suppressing chickweed. Annual crops once established can also suppress this weed. Summer fallowing must be through in the spring and late fall to keep chickweed growth in check.
Higher Seeding Rate: Research carried out at Lacombe Research Station has shown that a high seeding rate reduces weed densities and is effective in suppressing weeds
Use Certified Seed for Planting: Common chickweed often spread via the sale of contaminated crop seeds. Use of certified seed for planting would ensure competitive crop stand. |
| Chemical Control: |
Pre-seeding (Weed Burndown) Application: Glyphosate applied prior to seeding is registered for common chickweed control in all crops.
Spring In-crop Application: common chickweed seedlings can be controlled in-crop with several herbicides. For details on these herbicide choices, please see "Herbicide Selector Tool" on The Roping the Web |
